This invention relates to an improved shipping bag for powder or granular material.
To obtain a desired labor saving effect in the transportation of the powder or granular material, there has been a bulk cargo system where the powder material is directly loaded on the transportation means such as ship, vehicle and the like which are likely confronted with a risk of upsetting when the ship or vehicle lists on running with movement of the goods along the listing direction.
In order to avoid the foregoing risk, a various types of the shipping containers in convenient shape and size for transportation have been proposed and practised.
The shipping container of square shape including cubic or rectangular shape is preferred to maximize the load capacity, notwithstanding the conventional cubic or rectangular container is insufficient to obtain a maximum load capacity as the container when filled with the material is deformed under the pressure of the material into a cylindrical shape which when stacked in the hatch produces undesired spaces with reduction of the load capacity.
To improve the above disadvantages and inconveniences, the inventor has developed a new shipping container which even when filled with the material is susceptible to maintain a prototype of the square container and generally comprises a square bag made of soft and tough sheet having an inlet at its top end and an outlet at its bottom end. Four corner portions of the square bag are partitioned respectively through four rectangular sheet pieces to form four corner spaces and individual sheet piece at its opposite ends is joined with the adjoining inner walls of the square bag and provided with a number of slits in multistage for passing the material into the corner space so that the bag even when filled with the material is maintained in a square form.
However, the shipping container of the aforementioned type has confronted with inconvenience in manufacture since the partition piece must be strongly joined with the inner walls of the square bag to avoid removal of the partition piece therefrom to be caused under the pressure of the material filled in the bag.
To improve the foregoing deffects, there is provided a further improved bag which is comprised of a square external bag of flexible sheet having an inlet at its top end and an outlet at its bottom end and a cylindrical internal casing of the same material as that of the external bag. The cylindrical internal casing at its circumference is joined with four inner walls of the external bag to form four corner spaces through four partitions of unjoined circumference of the internal casing and the partitions are respectively provided with a number of slits in multistage for passing the material uniformly into the corner spaces so that the bag when filled with the material retains a prototype of the square bag for convenient stacking of the shipping bags with an enhanced load capacity. The shipping bag of this type is very convenient in manufacture and there is no likelihood of removal of the internal casing from the bag under the pressure of the filled material.